Multi-mode multi-frequency power amplifier

A mobile terminal device comprising a multi-mode multi-band power amplifier including:

• a controller;
• a wide-band amplifier channel;
• and
• a fundamental impedance transformer;
• wherein:
• the controller is configured to receive an external signal, and output a control signal according to the external signal;
• the wide-band amplifier channel is controlled by the controller, configured to receive single-band or multi-band RF signals through an input terminal, perform power amplification of the RF signals, and output amplified RF signals through an output terminal;
• the fundamental impedance transformer comprises a first segment shared by the RF signals in a plurality of bands, a plurality of second segments respectively specific to the RF signals in each of the plurality of bands, and a switching circuit coupled between the first segment and the plurality of second segments;
• the first segment is coupled with the output terminal of the wide-band amplifier channel;
• an optimal output fundamental impedance of corresponding bands is formed at the output terminals of the plurality of second segments;
• and
• the switching circuit is controlled by the controller to separate the RF signals subject to power amplification to the plurality of second segments in a switchable mode for multiplexed outputs, wherein each output corresponds to one band.